Suspended solids, petroleum hydrocarbons (C14-C28) (PH), benzo(a)pyrene (B(a)P), heavy metals (Pb,
Cd, Zn, Cu, Hg), and pH were analyzed in storm water runoff samples collected at five sites in different areas
of Vilnius city during three rain episodes in May-June, and at one site characterized by intensive traffic conditions
during six rain episodes in May-October 2007. The concentration of xenobiotics investigated in samples
was highly variable, depending on the sampling site and rainfall intensity. The evaluation of the toxicity
of storm water runoff samples to rainbow trout was undertaken. Alterations of fish biological parameters
(mean growth, white blood cell count) revealed significant differences in the toxic effects of storm water runoff
samples depending on the runoff discharge point and chemical composition. The most significant decrease in
the growth of rainbow trout fry was induced by storm water runoff, with the highest concentrations of
benzo(a)pyrene and petroleum hydrocarbons.